A semiconductor device, such as a metal oxide semiconductor field effect transistor (MOSFET,) or an insulated gate bipolar transistor (IGBT), has a super junction structure in which a p-type semiconductor region and an n-type semiconductor region are alternately provided in a drift layer in order to compensate for a design tradeoff between a breakdown voltage and on-resistance (or an on-voltage). By using the structure, it is possible to increase an effective doping concentration of the drift layer and to improve the relationship between the breakdown voltage and the on-resistance (or an on-voltage).
However, in the semiconductor device having the super junction structure in a termination region, when an electric field is applied to a semiconductor region surface of the termination region, ions contained in an insulating layer formed on the semiconductor region of the termination region move in the insulating layer as a result of the electric field. Then, some of the ions moving in the insulating layer locally gather at a region of the insulating layer on the side of the semiconductor region with a strong electric field. As a result, the surface of the semiconductor region is locally charged by the ions gathering in the insulating layer on the side of the semiconductor region. When the surface of the semiconductor region is charged with negative ions in this manner, the depletion layer in the termination region is extended. As a result, an electric field in a region of the outermost periphery of the termination region becomes stronger, and a breakdown voltage of the termination region is degraded. As a result, a breakdown voltage of the semiconductor device is lowered in some cases.